Devices for manually cutting circles from pieces of metal, plastic and glass have long been known and are commercially available. These devices typically consist of a central supporting structure and radially extending arm, pivotally attached to the central support. A cutting head is mounted on the arm for movement in a circular path about the supporting structure. The mounting arm is normally provided with a distance scale to facilitate setting of the head for cutting a circle of the desired diameter.
One example of a cutting device is disclosed in U.S. Pat. No. 5,014,436. The disclosed apparatus is for manually cutting circles from glass utilizing a center support structure, in combination with a rule having a distance scale thereon, and a cutting head adjustably mounted on the rule. Reversal of the position of the cutting head on the supporting rule adapts it for use with either of two different forms of cutting components. The central pivot support includes a suction cup type device to secure the apparatus in place during use.
Another example of the prior art circle cutting devices is disclosed in U.S. Pat. No. 4,878,409. The apparatus is for cutting circular arcs or holes in a picture mat and includes a flat base upon which the mat rests and a platform provided above the base. A crank mechanism and an extending perpendicular arm are provided for a cutting blade is adjustably mounted along the arm at an angle to the mat. The circles or arcs are cut in the mat by rotation of the crank mechanism with a diameter determined by the position of the cutting blade.
U.S. Pat. No. 2,735,486 discloses a device for cutting an abrasive disc or gasket. The device includes a table and spindle extending upwardly from the table through the material to be cut. A knife is mounted on an arm extending from the spindle and parallel to the table. The arm is pivoted around the spindle to cut the material.
U.S. Pat. No. 4,773,798 discloses a portable washer cutting device. The device as disclosed comprises a pair of enclosures to be interconnected and operative to rotate to progressively close the gap between the enclosures. A cutting knife is secured in one enclosure to progressively engage a flat washer blank with each rotation of the enclosure. The enclosures are rotated about a common spindle with respect to each other.
Numerous other circle cutting devices are disclosed in U.S. Pat. Nos. 4,060,893, 2,269,510 and 5,007,320. All of the above-noted devices are limited by their capacity, dimensions and ability to cut specified material. Some of these devices are limited to cutting holes in sheet goods of a predetermined size.
A demand continues in the art for a device that is able to cut circles from sheet materials and in particular sheet metal, plastics and other malleable materials to precise specifications. There is further a need for a device that is convenient and simple to use and relatively inexpensive to manufacture.